Thermostat.



H. A. STERN.

THERM'0STA'I'.'

' APPLICATION FILED JULY 22,, 1911' I 1 1 1 O, 1 53. Patented Sept. 8,1914.

A WAX/mama BMW/u m a. 82 m w .44.. z. W

UNITED stra'r as PATENT OFFICE.

v HALFDAN A. STEEN, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE. ASSIGN-MENTS, 'I'O ALLIS-CHALMERS MANUFACTURING COMPANY, A CORPORATION OFDELAWARE.

THERMOSTAT.

To all whom it may concern:

Be it known that I, HALFDAN A. STEEN, subject of the King of Norway,residing at Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented certain new and useful Improvements inThermostats. of which the following is a full, clear, and exactspecification.

My invention relates to thermostats.

In the operation of electrical apparatus, it is often'necessary that anoverload or other abnormal condition be allowed to exist for a definitelength of time before causing an interruption of the circuit. It is alsooften desirable that the length of time during which such overloadorother abnormal condition may continue vary in inverse sense to theextent of such condition.

It is the object of my present invention to provide a device foraccomplishing these ends which has certain advantages over thoseheretofore proposed.

In carrying out my invention there is provided a thermostat the heatingof which is obtained by a coil which is movable relatively to the memberor members to be heated, this relative movement beingproduced to bringthe parts into proximity upon the occurrence of a predetermined overloador other abnormal condition. The heating coil may be supplied from anysuitable source, but preferably with current which varies in the samesense as doesthe overload; and may be either always in circuit orconnected in circuit only upon the occurrence of the overload or otherabnormal condition. The thermostat, upon being heated sufliciently,causes the tripping of the protecting circuit-breaker.

The various novel features of my invention will appear from thedescription and drawings, and will be particularly pointed out in theclaims.

modified embodiment of my invention.

The device to be protected, shown as an alternating current generator10, is connect- .ed to the circuit 11 through a circuit-breaker '12.This circuit-breaker is biased to open position, but is normally held inclosed position by a holding coil 13 acting on a latch 14. The coil 13is shownconnected as a. no-

Specification of Letters Patent.

' Application filed July 22, 1911.

Serial No. 639.970.

'13 is completed through the contacts 15 of a suitable thermostat 16;the thermostat shown has two members which on heating expanddifferentially to cause relative movement between the contacts 15.

The thermostat is heated by a heating coil 17. which is not fixedrelatively to the thermostat proper but is mounted on an extension 18 ofthe pivoted armature 19 of an overload responsive device having a core20 and a coil 21. This coil 21 is connected in any suitable manner, asin series, so as to carry a current proportional to that supplied by thegenerator 10. The heating coil 17 may be supplied with current in anysuitable manner, one preferred arrangement being to connect it to a coil22 mounted on the core 20 and acting as the secondary winding of atransformer of which the winding 2]. is the primary. The connectionbetween the heating coil 17 and the secondary coil 22 may be either apermanent one, as shown in Fig. 3, or one which is only closed upon thelifting of the armature 19, being broken at the switch contacts 23 and24 when the armature 19 is in its lowest position, as shown in Fig. 1.

When the current supplied by the generator '10 is below thepredetermined value for which the overload device is set, the armature19 remains in its lowest position, as shown in Fig. 1. At that time thecircuit of the coil 17 may be interrupted as shown in Fig. 1 or may becomplete on account of the permanent connection shown in Fig. 3. Onaccount of the distance from the heating coil 17 to the thermostat 16,the heating coil, even if energized at this time, will produce no effecton the thermostat. If the current supplied by the generator 10 exceeds apredetermined value, the overload responsive device lifts its armature19 and brings the heating coil 17 into close proximity to the thermostat16, as shown in Fig. 3, at the varies in inverse sense to the currentsup- Patented Sept. 8, 1914. i

the contacts 15, thus denergizing the'holding coil 13' to cause-thetripping of the circuit-breaker 12. If before the thermostat.

16 has deflected sufiiciently to cause the sep-- 4 .aration of thecontacts 15 the current supplied by the generator should drop below andseparate the .heating coil 17 from the heating coil 16. The thermostat}will then cool, and be ready for operation thenext time the currentsupplied by the generator 10exceeds the'predetermined value.

Many modifications may be made in the precise arrangement shown anddescribed, and I aimto cover all such which do not involves. departurefrom the spirit and 20 scope of my invention" asset .forth in thefollowin claims.

What claim as new is: x y '1. In a circuit protecting device, a ther-.mostat, a heating coil therefor, said heating 2'5 coil beinginovable-relat-ivelymo the thermo-j' stat, and means responsive to'abnormal'conditions in the circuit to be 'p'rotected for moving theheating ,coil into proximity to the thermostat. I 2. In combination, athermostat, a heating coil thereforcarrying acurrent which varies in thesame sense as does that in the circuit toybe protected, and means formoving said heating coil relatively to the thermostat.

coil therefor, said heating coil being movable relatively to thethermostat, a. device for moving said heating coil into proximity'to thethermostat. when the current in a circuit 40 to be protected reaches anabnormal value,

coil therefor, and means for controlling the 4 5 distance between theheating coil and ther- .3. In combination, a thermostat, a heating1.11o,ios

mostat by variations in the current in a circuit to be protected.

5. In combination, a thermostat, a heating coil herefor, and means for"controlling bot the 'stance between the heating coil and the thermostatand the current. in the heating coil by variations in the current in acircuit I to be rotected. the predetermined value fornwhich the over-'10 load device is set, the armature 19 will'dr'op 6. combination,electromagnetic device comprising a plurality of r elativel movableparts and a current-carryin coi, and'a'thermost-at operatively associasaid electromagnetic device, said electromagnetic device. producing enerfor o eratin said thermostat when sai relative y movalile'pa'rts are inthe sitions occupied by them on the passage 0 current of a predeterminedvalue through said coil.

with I 7. In a circuit protecting device, a thermostat, a coil carryingcurrent proportional to that flowing 'in the circuit to be protected andmeans cooperatively associated with said current-carrying coil and said.thermostat for roducing heat in the thermostat and varying the distancebetween the thermostat and the heat-producing means when an abnormalcondition exists in the circuit to be protected.

' 4 8. In combination, an electromagnetic device comprisingfixed andmovable parts, a current-carrying coil, and a thermostat operativelyassociated with said electromagnetic device, said electromagnetic deviceadapted to produce heat in said thermostat when the movable art is inthat osition to which it is moved an abnorma condition of the current insaid coil.

Milwaukee, Wis, July .7, 1911.

c In testimony whereof I aflix my signature,

in the presence of'two witnesses.

' I-IALFDAN A. STEEN.

Witnesses: G. B. SCBLEY, .CHAS. L.,BYnoN.

